Indicator



L, E. DODGE 2,175,987

INDICATOR Filed July l, 1936 Oct. 10, 1939.

2 Sheets-Sheet l INVENTOR f, wf.

L. E. DODGE Oct. 10, 1939.

INDICATOR Filed July l, 1956 2 Sheets-Sheet 2 INVENTOR Patented Oct. 10, 1939 UNITED STATES PATENT OFFICE INDICATOR Lyman E. Dodge,

Morris Township,

Morris County, N. J., assignor to Frank C, La Mar,

This invention relates to electrical fuse devices, especially to integrity indicator means for cartridge type fuses, and more particularly to the class of such integrity indicators in which the indicator device is formed as a unitary structure having an entity distinct from that of the cartridge fuse or other type of fuse with which the indicator device is intended to be assembled in use.

Among the requirements which are desirably to be satisfied by a fuse-integrity indicator intended for assembly with a cartridge type fuse, and to provide for which is the general object of the present invention, is the need that the indicator device shall be capable of assembly readily with,

and attachment to, the fuse cartridge, or to the spaced-apart electrical terminals by which the fuse is contacted and thereby included in the Working circuit to be protected; also that such an integrity indicator shall be adaptable for use with cartridge fuses of generally standard sizes and types, though differing in non-essential details; also that the adaptation of the indicator to a given type of fuse can be effected without alteration in the structure of the fuse cartridge by a user, and that if any alteration of fuse cartridge, or of the integrity indicator, must be made by the manufacturer, in adapting the indicator to one or another make of fuse cartridge, such alteration shall be of an inconsiderable character, and may be performed at the manufactory instead of at the place of installation of the cartridge fuse and indicator.

A further requirement is to have the integrity indicator so conjoined with the fuse cartridge structure in use that the indicator will not be displaced by the vibrations and shocks encountered ordinarily in the use of such protective devices; also that the integrity indicator shall be so disposed With relation to the fuse cartridge that its presence will not interfere unduly with manipulation of the fuse cartridge during inspections, adjustments and renewals thereof.

Many of the integrity indicators at present applied to cartridge fuse assemblies for the aforesaid purpose, fail to satisfy the foregoing requirements in many respects, and none of such indicators are to be regarded as meeting all of the requirements in a completely satisfactory manner.

Among the outstanding deciencies that have been characteristic oi some of the fuse-integrityindicators now on the market, may be mentioned the tendency to shake away from the cartridge and fall into positions where they cause shorts,

1936, Serial No. 88,331

or crosses, in the electrical working circuit sought to be protected by the fuse, and the integrity or condition of which is desirably to be indicated reliably at all times; also the tendency to become loose to such an extent that the electrical contact is impaired, or broken, even if the indicator is apparently in place and operatively connected, a defect Which is particularly dangerous for the reason that a defective circuit condition may exist Without being signalled, the normal appearance of the indicator being deceptive.

Where indicator devices have been permanently attached to the structure of the fuse cartridge, as by solder or other form of metallic union, or by connections which make it necessary to remove the fuse Cartridge whenever the integrity indicator is removed, certain inconveniences may arise, so that it is desirable to pro- Vide for easy removal of the integrity indicator while the fuse cartridge remains in place, and the present invention has for an object the provision of means to permit such independent withdrawal of the indicator.

Another object oi the invention is to render more convenient than usual the operation of testing either the fuse or the indicator, or both.

Other objects and advantages will appear as the description of the particular physical embodiment selected to illustrate the invention progresses, and the novel features will be particularly pointed out in the appended claims.

In describing the invention in detail and the particular physical embodiment selected to illustrate the invention, reference will be had to the accompanying drawings and the several views thereon, in which like characters of reference designate like parts throughout the several views, and in which:

Figure 1 is a view in vertical longitudinal section of a protective device for electrical circuits in which a fuse cartridge element is shown in assembly with a support and with an integrity indicator element; Fig. 2 is a View in section, on the line 2 2 of Fig. 1, viewed n the direction of the arrows at the end of the line; Fig. 3 is a view in section on the line 3 3 of Fig. I, the view being taken in the direction indicated by the arrows at the end of the line; Fig. 4 is a detail View in perspective of a bracket element for holding both the fuse cartridge element and the integrity indicator element, the bracket element being taken separately; Fig. 5 is a view in side elevation oi a iuse cartridge with a modified form of integrity indicator shown in section, the fuse cartridge and integrity indicator being shown as assembled upon a supporting base of which only a part is shown; Fig. 6 is a view in perspective upon a smaller scale, of a fuse cartridge element, like that of Fig. 5, with the contact terminals in place ready to receive an integrity indicator element; Fig. 7 is a view in perspective of an indicator element such as that shown in Fig. 5, taken separately and ready to be assembled with the structure of Fig. 6; Fig. 8 is a view in sectional elevation of a modiiied assembly of integrity indicator, fuse cartridge and supporting base, the latter being broken away to reveal the attachment structure; Fig. 9 is a detail View, showing the attachment bracket of Fig. 8 taken in vertical section; Fig. 10 is a fragmentary detail view of the left-hand end of the modification of Fig. 9 illustrating the manner in which the attachment of the hidicator clip is eiected; Fig. 1l is a detail view showing the bracket of the Fig. 8 structure taken separately; Fig. 12 is a View in side elevation of another modification of integrity indicator with its attachment clips assembled with a fuse cartridge upon support of which part is broken away to reveal the attachment structure at one end of the assembly; Fig. 13 is a View in end elevation of the structure embodied in the modification of Fig. l2; Fig, 14 is a detail View in perspective taken separately, on a smaller scale, of an integrity indicator' element of the modified form shown in Figs. 12 and 13; Fig. 15 is a fragmentary detail view in sectional elevation of the integrity indicator of Fig. i4 shown in assembly with a fuse cartridge of the knife blade type, upon a support of which part is broken away.

In a now preferred embodiment of the present invention selected for illustration and description, and referring first to the structure illustrated in Figs. 1 to 4, inclusive, the member designated generally by the reference character F is an electrical fuse of the cartridge type, the part i l thereof being a barrel or cylindrical body of insulating material conning the fusible element l2 indicated in Fig. l and which, according to conventional usage, has suitable electrical connections (not shown) with metal terminal tips I3 and i4 screwed upon threaded thimbles or nipples l5.

In. the instance illustrated, the fuse cartridge F is held in operative position by metal clips C', C" of novel forrn, which include the usual feet I5 and upright spring members 21 and 28, made of flat, resilient sheet metal, bent to embrace the tangs T and T of the fuse cartridge structure, the feet l5 being secured to a base block l'l of insulating material by screws i8, the heads I9 of which are set against shoulders 20 of recesses 2| which are sealed with a suitable plastic 22.

These screws may be desirably, as shown, tapped into straps 23, 24, each furnished with a binding screw 25, of which only one is shown, and which constitute the terminals by which the protective device as an entity is connected into the electrical circuit to be protected.

The structure above identied is of a conventional type, and intended to be merely illustrative, it being understood that the upright spring members 2l and 28, extending upward from the feet le, as shown in Fig. 3, are so bent as to make good electrical and mechanical connection with the tangs T and T, so that a stout pull is required to remove the fuse plug F from its clipped position shown, in which its contained fuse element l2 operates normally to protect the circuit, in known manner.

In order to afford a desirable visual and attention-arresting indication of the fusing of the element |2 by passage therethrough of an electrical current of predetermined strength, provision is made, pursuant to the present invention, or an indicating device designated generally by the reference character I and which comprises an elongated body mounted upon the cartridge F by means of a pair of spaced exterior terminals 28 and 29" adapted to be coupled removably with lugs 3| and 32, each of which is offset from an integral post or bracket 26 which is desirably formed integrally with the clip springs 2l' and 28 from a single piece of sheet metal.

Each lug 3|, 32, is formed with a keyhole slot 30 adapted to receive a complemental grooved connector stud 33, one of which is aflixed to each of the exterior terminals 29 and 29, at the under side thereof, the studs 33 being so disposed, relatively to the spaced-apart positions of the lugs 3|, 32 when the clips C and C are assembled upon the support l1, as shown in Fig. 1, that when one stud 33 registers with the larger orifice of the keyhole 30 in one of the lugs 3|, the stud 33 on the other terminal as 29 will be in registry with the corresponding large orifice of the other keyhole 3|), and so the studs 33 can be entered simultaneously into the complemental portions of the respective keyholes, and when the indicator element is moved bodily lengthwise, the studs 33 will be moved into the narrower slot ends of the keyholes 30 respectively and the walls of those slots will grip firmly the grooved parts of the studs 33, as shown in Fig. 1, making a good rubbing electrical contact therewith.

It is to be noted that the indicator device herein shown and described is merely an illustrative example of numerous such integrity indicators which may be substituted at will in the protective assembly embodying the idea of means underlying the present invention.

The connection between the elongated body of the indicator device I and its end-supporting exterior terminals 29 and 29 is effected, in the instance shown, by means of metal caps 34 and 35, one for each end of the body, upon which the caps are fitted snugly, being preferably held thereon positively as by the use of self-driving screws 36 or other suitable means.

The indicator proper may conveniently take the form of a neon-filled discharge lamp N, with terminals 4| and 42 the former of which terminals is soldered to the inner end of the exterior terminal 29" while to the other lamp terminal 4'2 is connected one end of a resistance R, preierably of the order of 50,000 to 100,000 ohms, from the other end of which a conductor 43 leads to the inner end of the exterior terminal 29 as shown in Fig. 1.

The elongated body I is preferably made of insulating material, and former with a body chamber 44 to receive the lamp N, which can be Viewed through an orifice 45, and the chamber 44 is shown as large enough to accommodate the resistance R, the body having also a channel 46 extending lengthwise to receive the conductors 4|, 42 and 4'3, this channel being preferably closed by a suitable plastic 41, so that all parts of the indicator proper are snugly held in their proper insulated position.

It will be clear that while the provision of metal caps 34 and 35 is advantageous, by reason of their strength, nevertheless adequate structural strength may be secured by forming them of insulating material, where such provision is preferable.

The tight metal-to-metal engagement between the studs 33 and the walls of the studs 30 insures the maintenance of a good electrical connection, and as long as the integrity indicator is allowed to remain upon the fuse cartridge, it will be included in a shunt circuit of the working circuit protected by the fuse F.

While the fusible element I2 of the fuse cart- .ridge remains intact, the current will find an easier path through I2 than through the lamp N, by reason of the high resistance R. in series with the lamp, but the latter will be energized whenever suflicient current is diverted therethrough by fusion of the fusible element I2; whereupon a visible and attention-arresting indication of the impaired circuit condition will be yielded by the characteristic neon glow, visible through the window 45.

The integrity indicator I, above described, may be removed at any time by a sliding movement bodily thereof, to permit manipulation. of the fuse cartridge F, and after removal of the fuse cartridge, the screw cap I3, or the screw cap I4, or both, may be removed, while the clips C' and C" remain in place, so that they need not be disturbed in the ordinary course of inspections, adjustments and replacements incidental to use of such a protective device.

However, if at any time it is desired to remove the clips C and C, this may be done readily after first removing the screws I8 and 25. The clip structure, as C', presents a very strong compact design, as shown in Fig. 4, and combines resilience with sturdiness to an unusual degree.

In Figs. 5 to '1 is shown` a modification in which contact members 3I and 32a: are provided, each of which, as shown in Fig. 6, has a shank 40, with an elongated slot 40x to iit upon. a tang T of a knife blade type cartridge fuse, as illustrated. In the lugs 3Ix and 32a: are formed keyhole slots 30x, designed to cooperate with studs 33x which are set in the periphery of a modified form of integrity indicator I5 and coact with the contact clips 3 Ix and 32x in the same manner as has been above described with reference to the stud-and-keyhole connections illustrated in Figs. l to 4.

The integrity indicator I5 has an elongated body of insulating material, channelled at 50 and having a threaded orifice 5I in which may be seated a. lamp L of the ordinary glow type, or of any suitable form to give an attention` arresting signal when` current passes in the shunt, which may be traced through clip 3Ix, stud 33m, conductor 52, central terminal of lamp to the lamp and from peripheral terminal 54 of lamp to lamp socket 55, conductor 56, resistance R, conductor 51 and stud 33x to clip 32x.

This novel form of integrity indicator I5 exhibits no metal parts at any region other than beneath its barrel, and may be used to special advantage where the exposure of metal parts included in the working circuit must be guarded against. n

In the modification illustrated in Figs. 8 and 9 the reference character F8 designates a cartridge fuse of the ferrule type, comprising a barrel II of insulating material which encloses a fusible element I2 in electrical connection (by means not shown) with a metal terminal cap I3 at one end and a similar metal cap I4 at the other end, which caps are tted, as shown in Fig. 9, into contact clips 61 and 58, the feet 66 of which, as shown in Fig. 8, are held down by straps 64 and 65, through which extend screws I8, xed in the bottom of a supporting base |131, the straps being provided with binding screws 63 and 62 which constitute terminals by which the protective device with its fuse F8 may be included in seriesy in the working electrical circuit to be protected.

As thus far described, the ferrule type fuse cartridge is supported in the conventional manner, but the clips 61, 68, are not completely of conventional form, inasmuch as they are formed, in pursuance of the present invention, with upright integral sheet metal posts 59 and 69 each of which terminates in a bracket as 1I and 12 extending outwardly at each end of the cartridge fuse structure, and each having a saddle or clip 13 projecting upwardly and in each of which is seated an end ferrule, as 14, 15, of the elongated body of an integrity indicator which is designated by the reference character I5 for the reason that it may illustratively be of the general type shown in Fig. 5. It diifers therefrom however, in the form of its attachment to the supporting brackets, as already described. Its indicator lamp L responds to energization by current diverted from the working circuit upon fusion of element I2 of the fuse cartridge, whereupon the lamp L glows, furnishing the desired indication as to condition of the working circuit, with which the indicator is in shunt through brackets 1I, 12, uprights E9 and B9, feet 63, straps 54, S5 and terminal binding screws B2 and 63.

In view of the reatively short length of the cartridge fuse F8 which may be of the onetime fuse type, although this is not an essential feature of this modification, the brackets 1! and 12 are so disposed as to extend over the binding screws 62 and 63 respectively, and in order to permit easy access to these screws, the brackets respectively are formed each with an orice 10, through which a screw driver can be passed, in order to operate the binding screw therebeneath.

It will be noted also that, as the feet S6 extend inwardly with respect to the straps 64 and G5, which they underlie, an orifice or gateway 11 is provided (see Figs. 3 and 9) to permit the straps to extend from screws I8 to the binding screws 82 and 63y respectively.

It will be apparent that the integrity indicator I5 can be withdrawn from the assembly of Fig. 8, and then the cartridge fuse F8 can be withdrawn, tested, replaced or substituted by another, without necessitating any readjustments of the clips 59 and 59 cr of the brackets 1I and 12, so that the supporting structure remains ready to receive, first the fuse cartridge, and then the integrity indicator, without any need for readjustments of the cooperating parts.

In Figs. l0 and 1l is illustrated a modication which provides a separately formed bracket structure B the structural detail of which is well il.- lustratcd in Fig. 1l, while the manner of assembling it is best shown in Fig. 10. It comprises a foot 13, an upright 19, and a bracket part E!) extended in parallelism with the foot, and in the same direction therewith. The foot an open slot 8l, which permits it to be tucked in, as shown in Fig. 10 in dotted lines, beneath the head 82 of a binding screw 85 which serves as a terminal for that end of the fuse structure, being connected by a strap 8A with the foot i@ of a conventional clip 26 for the fuse cartridge F10, the end ferrule I3 of which is held in the clip, and so included in series in the working circuit; a similar arrangement (not shown) serving at the other end of the protective device now being described. The foot 18 of the bracket structure B overlies the strap and offset lugs to help to keep these superimposed parts in alignment so that the bracket part t@ is properly presented with its spring sides 88 constituting a clip in parallelism with the major axis of the elongated body of the integrity indicator 11o which it is to support and include in shunt with the fuse F10, in the manner hereinbefore described. The ferrule 8l at each end of the indicator body is connected electrically with the indicator means (not shown) as already described.

In this form or the device also, it is possible to withdraw the indicator, and then the fuse cartridge, while the bracket B remains in place, and at any time the bracket also can be removed, repaired and replaced or substituted by another, or the fuse cartridge may be left without an indicator, if so desired. This form of the device lends itself readily to assembly with existing structures, wherever there is a bin-ding screw so disposed as to permit the introduction of a bracket foot I8 like that shown in Figs. l0 and l1.

he underlying idea or" means of the present invention is illustrated in Figs. 12 and 13 as embodied in still another modiiication, in which the part designated by the reference character 112 is an integrity indicator element which may have an interior structure corresponding to any of the types hereinbefore illustrated and described, or known in the art, or otherwise suitable to yield a visible and attention-arresting signal when the fusible element in the cartridge type fuse F12 is fuse-d by passage of current of a predetermined strength in the circuit to be protected.

For illustrative purposes, the integrity indicator 112 may be considered as identical with that shown in Fig. 5, and the interior structure of which has been described with reference thereto.

Exteriorly, the elongated body 112 of Figs. 12 and 13 is provided with contact terminals Si and 92 when viewed in end elevation, as shown in have substantially the contour of the numeral B, or of a dumb-bell, the upper lobes 93 and SQ being constituted by metal caps each of which is connected electrically with the indicator lamp L by a conductor such as those shown at 52 and in 5, in series with a suitable resistance, as R.

The lower or free lobes 95 and may desirably be integral metal extensions, either solid or shellform, of the lobes 53 and Ell, so that the integrity indicator constitutes a complete self-contained entity maketable as such (see Fig. 14).

As one suitable form of complemental terminal clip, to be engaged with the lobes 95 and 96, provision is made of a pair of spring clips B', one for each end lobe 85, 9S, but only one oi the pair being shown and described herein by Way of illustrating both, as they may be and desirably are identical in structure.

In essential respects, the spring clips or brackets B may be regarded as like those designated B and already described with reference to the disclosure in Figs. 8 and 9 having an apertured foot 99 adapted to underlie a connector strap 66 like that of Figs. 8 and 9, and to be transiiXed by the screw i8 which holds the strap in place upon the base ll where each such strap serves as a binding terminal by which the protective assembly is included in the electrical working circuit to be protected, each being provided with a terminal binding screw, as 91. In further correspondence with the bracket B, the bracket B has an upright l @t apertured at 'll to pass the strap 66, and it has also integral sheet metal spring clips l 0I to support, and make electrical Contact with, the metal end ferrules 95, 96 o the integrity indicator 112, whereby the latter is included in shunt in the Working electrical circuit.

Each of the clips lill is provided with lugs 98 adapted to prevent end shake of the integrity indicator, which is, accordingly, held tightly in place, just as the fuse cartridge F12 is held by the clips Gl, (it, which are similarly provided with lugs 98 to prevent end-shake of the fuse cartridge F12 (see Fig. 13).

rThe behavior of such clips or brackets as those shown at 51 and lill, is well understood, and Very reliable, so that in view of the short, sturdy character of each bracket B a very economical and safe form of connector is provided by this novel form of the invention. Each bracket B will preferably have also an orifice 1G, through which to gain access to the binding screw 91 when the indicator 112 has been removed.

Still another modiiication of the fuse indicator and attaching means is illustrated in Figs. 14 and l5, which show in assembly with the tang T3 of a knife-type cartridge fuse F15, a bracket B which may be in general of the form shown in Figs. 12 and 13, and these described as assembled with a ferrule 'type fuse cartridge F12, and with an integrity indicator 112.

The indicator 111 of the present modication has end terminals di and 92 identical in 8 shape and in arrangement with those shown and described with reference to Figs. 12 and 13.

The elongated indicator body 111 is, however, of novel structure, in that it comprises a prism-like tube of transparent insulating material such as Bakelite or malleable glass having a bore |02 lled with inert gas, say of the neon discharge type, and suitable terminals (not shown) to energize the gas, so that the tube as a whole will glow when energized by the passage of a proper current after rupture of the fusible element in fuse cartridge F15.

Although 1 have particularly described one particular physical embodiment of my invention and explained the operation, construction and principle thereof, nevertheless, 1 desire to have it understood that the form selected is merely illustrative, but does not exhaust the possible physical y embodiments invention.

What I claim as new and desire to secure by Letters Patent oi the United States, is:

1. In an integrity indicator device for a cartridge fuse, in combination, an elongated body, an indicating means carried by said body, a pair of contact terminals fixed to the ends of said elongated body and connected electrically with said indicating means, extending respectively from said body into positions each adjacent to one end of the fuse cartridge structure, and a pair of clip or connector members each comprising a bracket positioned suitably to be connected with one of said indicator contact terminals to form a readily attachable-detachable mechanical and electrical connection therewith, and each of said clip members being adapted to be associated initimately with, and thereby connected electrically with, one of the clip springs by which said fuse is included in the working circuit to be protected, the brackets respectively being disposed in position to hold the indicator bodily above the level of the fuse cartridge.

2. A protective device comprising the elements of the idea of means underlying my combined and cooperating as set forth in claim 1, and further characterized by having said connector brackets and integrity indicator terminals formed with complemental keyhole and fixed stud coupling means adapted to be inter-engaged firmly in non-rotatable relation.

3. A protective device comprising the elements combined and cooperating as set forth in claim l, and further characterized by having said connector brackets and integrity indicator terminals formed with complemental keyhole and stud coupling means, the stud means including a pair of fixed grooved studs projecting from said integrity indicator structure in spaced-apart positions, and the keyhole slots being formed in lugs upon said brackets similarly spaced in position to cooperate with said studs, said co-operative engagement being effected exclusively by unidirectional movement of the indicator in a direction lengthwise thereof and along which the indicator is normally gravity-biased when in use.

4. In an integrity indicator device for a cartridge fuse, in combination: an elongated body, an indicating means carried by said body, a pair of Contact terminals xed to the ends of said elongated body and connected electrically with said indicating means, occupying positions upon said body so spaced that each such terminal is adapted to be disposed adjacent to one end of the fuse cartridge structure, and a pair of bracket members each having a part positioned suitably to be connected with one of said indicator contact terminals to form a ready attachable-detachable mechanical and electrical connection therewith, each of said bracket members having also an upright post and a foot associated intimately with one clip spring on the support by which said fuse cartridge is included in the working circuit to be protected, the brackets respectively being disposed in position to hold the indicator bodily above the level of the fuse cartridge.

5. As an article of manufacture, a connector bracket member for a protective device of the class described, said bracket comprising in a unitary structure a foot, an upright post and a bracket part provided with means to effect an easily attachable-detachable mechanical and electrical connection of the complemental keyhole and iixed stud type with an integrity indicator element, for supporting the indicator and including the same electrically in a shunt of the electrical working circuit to be protected, said bracket having its foot constructed for removable connection directly with a fuse cartridge support in series with said working circuit.

6. A bracket member of the class described comprising in a unitary sheet metal structure a foot, having an open ended slot to permit insertion of said foot under the head of a binding screw; a post bent up from said foot, and a lug bent from the upper end of said post over said foot, having upwardly extended parts adapted to clip an end terminal of a fuse cartridge indicator.

'7. A bracket member of the class described, comprising in a unitary sheet metal structure a foot, having an open ended slot to permit insertion of said foot under the head of a binding screw; a post bent up from said foot, and a lug bent from the upper end of said post over said foot, having upwardly extended parts adapted to hold an end terminal of a fuse cartridge indicator, said lug being formed with an orifice through which a tool may be extended for engagement with the head of said binding screw.

8. An end-connection and supporting structure in a protective device of the class including a base provided with a pair of metal spring clips to receive a fuse cartridge and include the same in an electrical circuit, said device being characterized by a strap extending from each of said clips and a binding screw at the other end of each strap, a pair of brackets each having a foot assembled removably with said strap and a screw transxing said strap and foot to connect said foot and strap electrically and secure both to the base, each of said brackets having a part adapted to hold an end terminal of an integrity indicator in assembly with said fuse, and to connect it in a shunt of the working circuit.

LYMAN E. DODGE. 

